Portions of this disclosure are described in terms of, e.g., encoded signals for digital designs, product packaging (sometimes just referred to herein as “packaging” or “package”) and other objects. These encoding techniques can be used, e.g., to alter or transform how color inks are printed on various physical substrates. The alterations or transformations preferably result in a printed design carrying machine readable indicia on a surface of a physical object.
Various forms of signal encoding (or “embedding”) include, e.g., “steganographic encoding” and “digital watermarking.” Digital watermarking is a process for transforming physical or electronic media to embed a machine-readable code (or “auxiliary data”) into the media. In some cases the media is transformed such that the embedded code is “obscured” or “generally imperceptible” yet may be detected through an automated detection process. Obscured and generally imperceptible in this context means that the luminance/chrominance variations in the artwork due to the digital watermarking are not noticeable to a human viewer inspecting the package from a usual distance (e.g., 20 inches) under normal retail lighting (e.g., 50-85 foot candles), who has not previously been alerted to the existence of the digital watermarking.
Digital watermarking is often applied to electronic or physical objects such as printed objects, images, audio signals, and video signals. However, it may also be applied to other types of objects, including, e.g., product packaging, electronics such as circuit boards and CPUs, stickers, logos, product hang tags, line-art, software, multi-dimensional graphics models, and surface textures of such objects.
In this document we use the terms “digital watermark” and “watermark” (and various forms thereof) interchangeably.
Auxiliary data embedding systems typically include two components: an encoder (or embedder) that embeds the auxiliary signal in a host image or object, and a decoder (or detector) that detects and reads the embedded auxiliary signal from the host image or object. The encoder may embed the auxiliary signal by altering or transforming a host image or object to carry the auxiliary data. The detection component analyzes a suspect image, object or signal to detect whether an auxiliary signal is present, and if so, extracts or reads information carried in it.
Several particular digital watermarking and auxiliary data embedding techniques have been developed. The reader is presumed to be familiar with the literature in this field. Particular techniques for embedding and detecting imperceptible digital watermarks are detailed in the assignee's patent documents including US Published Patent Application Nos. 20150156369 and 20160217547; U.S. patent application Ser. No. 14/725,399, filed May 29, 2015, (issued as U.S. Pat. No. 9,635,378), and Ser. No. 14/842,575, filed Sep. 1, 2015; (issued as U.S. Pat. No. 9,819,950); International Application No. PCT/US2015/44904, filed Aug. 12, 2015 (published as WO 2016025631 A1) and U.S. Pat. Nos. 7,054,461, 7,286,685, and 9,129,277. Related technology is detailed in Assignee's U.S. patent application Ser. No. 15/073,483, filed Mar. 17, 2016 (issued as U.S. Pat. No. 9,754,341). Each of the patent documents mentioned in this paragraph are hereby incorporated herein by reference in its entirety, including all drawings and any appendices.
One aspect of the disclosure is an image processing method comprising: obtaining first color values representing luminance, color channel ‘a’ and color channel ‘b’ for a first color; obtaining second color values representing luminance, color channel ‘a’ and color channel ‘b’ for a substrate or a background color; obtaining first reflectance values for the first color at a machine-vision wavelength; obtaining second reflectance values for the substrate or the background color at the machine-vision wavelength; combining the first reflectance values and the second reflectance values to yield a reflectance difference; using one or more programmed processors, determining an encoded signal error that is associated with the first color values, the second color values and the reflectance difference; using one or more programmed processors, determining a color error that is associated with the first color values, the second color values and the reflectance difference; and combining the encoded signal error and the color error to yield a combined error, and evaluating the combined error to determine whether to transform digital imagery to carry an encoded signal.
Another aspect of the disclosure is an image processing method comprising: obtaining first color values representing luminance*, color channel ‘a*’ and color channel ‘b*’ for a first plurality of colors; obtaining second color values representing luminance*, color channel ‘a*’ and color channel ‘b*’ for a substrate or a background color; using one or more programmed processors, determining an encoded signal error that is associated with the first color values, the second color values, and a first machine-vision wavelength difference between the first color and the substrate or the background color; using one or more programmed processors, determining a color error that is associated with the first color values, the second color values, and the first machine-vision wavelength difference between the first color and the substrate or the background color; and combining the encoded signal error and the color error for each of the first plurality of colors to yield a plurality of combined errors, and evaluating the combined errors to determine a target color from the plurality of colors in terms of signal robustness and signal visibility associated with the first machine-vision wavelength.
Yet another aspect of the disclosure is a retail product package comprising: a first substrate comprising a first area; a sparse mark pattern printed within the first area with a first ink; an ink flood printed over the sparse mark pattern and the first substrate within the first area with a second ink, in which the second ink comprises a larger tack or adhesion with the first substrate relative to a tack or adhesion with the first ink, the first area comprising a first region comprising a layer of ink flood and a layer of first substrate, the first area further comprising a second region comprising a layer of ink flood, a layer of sparse mark pattern and a layer of first substrate, in which the first region and the second region comprise a spectral reflectance difference at a machine-vision wavelength in the range of 8%-60%.
Further aspects, features and advantages will become even more apparent with reference to the following detailed description, claims and accompanying drawings.